This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A061949 #15 Mar 08 2020 20:53:16
%S A061949 1,2,4,5,6,10,12,14,18,19,57,119,133,209,399,437,633,1102,3517,5719,
%T A061949 29849,38532,42759,198639,247801,421591,566561,819185,6781309
%N A061949 Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 20 (most significant digit on right).
%C A061949 This sequence differs from A029513 in that all least significant zeros are removed before concatenation.
%C A061949 No more terms < 10^7. [_Lars Blomberg_, Oct 25 2011]
%H A061949 <a href="/index/N#concat">Index entries for related sequences</a>
%e A061949 See A061931 for example.
%t A061949 b = 20; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[c, IntegerDigits[IntegerReverse[#, b], b]], b], #] &] (* _Robert Price_, Mar 08 2020 *)
%Y A061949 Cf. A029447-A029470, A029471-A029494, A029495-A029518, A029519-A029542, A061931-A061954, A061955-A061978.
%K A061949 nonn,base,more
%O A061949 1,2
%A A061949 Larry Reeves (larryr(AT)acm.org), May 24 2001
%E A061949 Edited and updated by Larry Reeves (larryr(AT)acm.org), Apr 12 2002; Aug 25, 2002
%E A061949 a(28)-a(29) from _Lars Blomberg_, Oct 25 2011